When asked to memorize the ten letters, D, R, S, S, A, Y, N, R, A, and B, Debbie reorganized them into the words BARNS and YARDS. This helped her remember the letters accurately at a later time. Which of the following tactics has Debbie used in order to simplify the process of memorizing the letters? 1) priming 2) rehearsal 3) self-reference 4) chunking